Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update August 28, 1999 at 04:45 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update August 2, 1999)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update August 2, 1999)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update August 2, 1999)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet to mildly active on August 27. Solar wind speed ranged between 553 and 717 km/sec. Solar flare activity was high. Solar flux was 223.1 (the highest solar flux value during solar cycle 23), the planetary A index was 13 (3-hour K indices: 3342 3332, Boulder K indices: 2331 3222). Region 8673 produced a couple of C flares and several sub flares. Region 8674 developed further and early on August 28 appears to have in excess of 80 spots (the highest number of spots in a single region during cycle 23). The region was the source of 3 M flares and is likely to produce M flares and perhaps even an X flare. A magnetic delta configuration is still present in the trailing part of the region and another magnetic delta configuration is evident just west of the region's center. Regions 8675 and 8676 were quiet and stable, as were regions 8677, 8678 and 8679. Region 8680 rotated off the visible disk early on August 28. A new region is developing very quickly in the northeast quadrant to the west of region 8676, should the current rate of development continue, M flares will become possible later today. Flares and CMEs A total of 4 C flares and 3 M flares were recorded on August 27. All the M flares had their origin in region 8674. The first was an M3.0 flare at 01:37 UTC (location of flare was confirmed by SOHO EIT images), no obvious CME was observed with this flare. A major flare, an M5.5/2N moderate duration event, was observed at 13:07 UTC. Again no CME was observed. At 16:35 UTC a long duration M3.0/2N event peaked. Again no associated CME or sweeps were observed. Region 8674 also produced an M2.8 flare at 01:02 UTC on August 28. A region a few days behind the northeast limb was the source of 2 significant coronal mass ejections during the day. The background x-ray flux is at the class C1-C2 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on August 28-29. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is poor. Coronal holes (1) Coronal mass M and X class flares (3) ejections (2) [Coronal hole indicator][CME indicator] [M and X class flare indicator] 1) Effects from a coronal hole could reach earth within the next 5 days. 2) Material from a CME is likely to impact earth within 96 hours. 3) There is a possibility of either M or X class flares within the next 48 hours. Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability. Active solar regions (Recent map) Solar Date Actual Location region numbered no. at Area Classification Comment sunspots midnight 8673 990819 14 S19W24 0440 CHO beta-gamma 8674 990820 72 S24W16 0770 FKC beta-gamma-delta 8675 990824 10 N19E40 0080 DAO 8676 990824 7 N25E34 0010 BXO 8677 990825 6 N07E46 0090 CSO 8678 990825 2 N16W67 0010 BXO 8679 990826 2 S31E44 0050 CAO 8680 990826 1 N22W87 0000 AXX Total number of sunspots: 114 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 9807 114.0 66.6 65.5 (+3.0) 9808 136.0 92.2 67.8 (+2.3) 9809 138.3 92.9 69.5 (+1.7) 9810 117.2 55.5 70.5 (+1.0) 9811 140.1 74.0 73.0 (+2.5) 9812 150.1 81.9 77.9 (+4.9) 9901 140.6 62.4 82.6 (+4.7) 9902 141.9 66.1 (84.9 predicted, +2.3) 9903 126.3 69.1 (86.4 predicted, +1.5) 9904 117.2 63.9 (90.0 predicted, +3.6) 9905 148.4 106.3 9906 169.8 137.4 9907 165.6 113.5 9908 164.7 (1) 107.8 (2) 1) Running average based on the daily 20:00 UTC solar flux value at 2800 MHz.. 2) Unofficial, accumulated value. The official value is typically 25-40% less. This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]